
graph = {}
graph['you'] = ['alice', 'bob', 'claire']

graph['start'] = {}
graph['start']['a'] = 6
graph['start']['b'] = 2

graph['a'] = {}
graph['a']['fin'] = 1
graph['b'] = {}
graph['b']['a'] = 3
graph['b']['fin'] = 5

graph['fin'] = {}

infinity = float('inf')
costs = {}
costs['a'] = 6
costs['b'] = 2
costs['fin'] = infinity

parents = {}
parents['a'] = 'start'
parents['b'] = 'start'
parents['fin'] = None

processed = []


node = find_lowest_cost_node(costs)
while node is not None:
    cost = costs[node]
    neighbors = graph[node]
    for n in neighbors.keys():
        new_cost = cost + neighbors[n]
        if costs[n] > new_cost:
            costs[n] = new_cost
            parents[n] = node
    processed.append(node)